1. Field of the Invention
The invention relates to a control device for a printing apparatus having a plurality of operation modes.
2. Description of Related Art
Various kinds of printing apparatuses are in use in which, when printing is carried out based on printing information input from an external device, letters, figures and the like commanded to be printed are printed in accordance with control codes, such as bold face, subscript, line feed, form feed and the like, contained in the printing information.
In addition, in order to enable more varied printing, the printing apparatuses have their own peculiar operation modes such as a high-speed mode for carrying out printing at high speed, designation of dot space and bit image and the like. These modes are also designated by the control codes, in particular, escape control codes (ESC sequence code) in the printing information.
In this case, the control codes including the escape control codes are usually peculiar to the printing apparatus or the manufacturer of the printing apparatus. For example, in DIABLO MODE, "ESC6" is a control code for BACKWARD-PRINT-MODE-ON, while the same is a control command code for PRINTABLE-CODE-AREA-EXPANSION in EPSON MODE, or for SELECT-INTERNATIONAL-CHARACTER-SET in IBM MODE. Thus, the same ESC sequence code has a different instruction in a different operation mode.
Therefore, a printing apparatus on the market cannot carry out the desired printing so long as the printing information is not compatible with the operation mode of the printing apparatus used. Thus, a printing apparatus has been developed in which an operation mode is selected from a plurality of operation modes, in compliance with the printing information, by an operator and the input printing information is printed in accordance with the selected operation mode.
However, in the above-described printing apparatus, it is required for an operator to know, before inputting printing information, the operation mode in which the printing information is to be printed and determine which one of the plurality of possible operation modes is compatible with the printing information desired to be printed for selection of the appropriate one of the operation modes. Therefore, the operation to select an operation mode becomes more complex and it is especially difficult for beginners to execute the complete printing operation.
In view of the above, a printing apparatus, disclosed in U.S. Pat. No. 4,968,159, has been developed. A plurality of operation modes are found in the printing apparatus and an operation mode which is compatible with the input printing information is automatically selected.
In order to provide in the printing apparatus the automatic selection of an operation mode, in compliance with the printing information, control codes, which are included within a predetermined amount of first input printing information, are analyzed to determine the operation mode in which the control codes exist. According to the determination, an operation mode in which the printing information is to be printed is automatically selected from the plurality of operation modes available. In the printing apparatus, since no complicated operation is required of an operator, operational mistakes do not occur and it is easy for beginners to use the printing apparatus.
However, in the above-described printing apparatus, any operation mode which substantially does not have any control codes cannot be distinguished from among the plurality of possible operation modes, because the operation mode which is compatible with the printing information is determined by control codes such as above-described ESC sequence codes included in the printing information to be printed. That is, if the operation mode of the printing information to be printed does not substantially have any control codes such as ESC sequence codes, the operation mode cannot be determined by control codes since the printing information does not have any control codes by which the operation mode is determined.
For example, a printing apparatus having two operation modes, such as the HP mode (Hewlett Packard mode) having ESC sequence code and the PS mode (Post Script mode) without ESC sequence code. If printing information of the PS mode, without ESC sequence code, is input to the printing apparatus, PS mode in which the printing information is to be printed cannot be distinguished from HP mode by analyzing ESC sequence codes since the printing information does not have any ESC sequence code.